This invention concerns intraoperative angiography for vascular reconstructive surgery, and more particularly, apparatus for injecting radiopaque dye into a new artery during arteriography.
Vascular reconstructive surgery has progressed significantly in recent years with the development of new surgical techniques producing obvious benefits to the patients involved. A detailed description of this surgery will not be attempted here, because this patent application concerns apparatus used in conjunction with such surgery and presumes a reasonable familiarity with the basic surgical procedures.
While pre-operative arteriograms are normally obtained and utilized in connection with vascular reconstruction, intra-operative arteriography (also abbreviated "IOA") has not become routinely practiced for various reasons, including the belief by some surgeons that intraoperative arteriography is not necessary, and the concern by surgeons for the damage to their personal health due to the cumulative effects of repeated radiation exposure they experience, should they conduct IOA with every arterial reconstructive procedure. The more recent experience with IOA indicates strongly that this procedure is more than merely useful, and in many cases will provide critical information that will call for immediate corrective surgery. More particularly, IOA can provide immediate identification of technical errors at the suture line, platelet thrombi, atherosclerotic debris, previously unrecognized or unappreciated stenosing lesions just beyond the distal anastomosis, or rotation or kinking of the graft, thereby enabling the immediate corrective surgery. Subsequent or unrecognized graft failure is thus obviated; unrecognized bleeding can also be found if extravascular pooling of the contrast medium occurs, particularly at sites remote from insertion of the needle used for the angiogram. The value of IOA in cases of vascular trauma is also evident, particularly to avoid constricting anastomosis in medium-sized or small arteries and to delineate unrecognized areas of injury. Further description of these known medical procedures is found in the article, "Routine Intraoperative Angiography" in Archives of Surgery, Volume 110, February, 1975, by Irving I. Dardik, M.D., et al.
The basic problem considered herein is the radiation exposure experienced by the surgeon during intraoperative arteriography because he is very close to the patient while he manually injects the radiopaque dye into the patient's artery, as x-ray radiation is directed to the area of vascular reconstruction. Even though the x-ray beam is collimated and the surgeon wears a lead vest or apron, there remains some radiation danger due to imperfect collimation and/or scatter, which on a cummulative basis can be detrimental.
The reason for the surgeon's close proximity to the radiation is the requirement for his personal and continuous control of the injection which he can maintain by virtue of his direct observation and his "feel" of the injectate flow and/or resistance to flow while the syringe plunger is operated by his thumb and fingers. With regard to this radiation danger, obviously the surgeon and his operating team feel more confident and clearly are more safe when they retreat behind a lead-lined wall or leaded glass window while the x-ray radiation occurs. Unfortunately the surgeon cannot carry out personal, manual injection while he is at a remote location.
One might consider a remote, electronically controlled injecting device which is invulnerable to x-ray radiation and which is operated by switches and levers in the radiation-safe location. While attractive in theory, such is not really feasible for the following reasons. A patient who receives the radiopaque dye during IOA is in the midst of surgery with new untested arterial grafts or other vascular reconstruction. An existing injecting machine such as the "Angiomat 3000" is designed for pre-operative angiography, where the injection rate is pre-set to be automatic and thus does not have features to sense and react properly to the many possible problems that could have developed or been discovered during surgery. Such a machine not only lacks the surgeon's versatility, it was not designed to deal with the intraoperative conditions. In fact, no machine is known that is able to register and simulate the surgeon's experienced "feel", judgment and reactions. Cost of equipment in medical care is another factor that must not be dismissed; highly expensive apparatus is avoided when not proven to be essential, and the problem or danger remains until a less expensive solution is found.
One might also consier providing a hose of about a 30-foot length filled with radiopaque injectate, with a needle on the remote end for insertion in the artery and a syringe on the near end behind the lead wall. This is highly impractical as it would require a fluid system starting in the non-sterile hallway with its destination in the patient's artery, via a hose lying on the floor or draped from one IV pole to another; also this would consume an excessive quantity of radiopaque dye to fill the entire length of hose, while only a small portion of the fluid would actually be injected.
For the reasons discussed above, intraoperative arteriography has not become a routine procedure; however the available evidence indicates IOA should become the rule rather than the exception. The present invention as described in subsequent sections, is an apparatus that permits the surgeon to have the benefits of conventional, manual injection in the immediate proximity of the patient during IOA, while he is actually at a remote location and behind lead-lined walls and safe from radiation. The invention is summarized below, followed by a detailed description of a preferred embodiment.